The present invention is directed to a bone plating system, and in particular to a system for the fixation of a canine humerus following a slide osteotomy.
Elbow dysplasia, including fragmentation of the medial coronoid process of the ulna (FCP), is the most common forelimb orthopedic disorder recognized to cause joint pain and lameness in large and giant breed dogs. Fragmented medial coronoid process (“FCP”) with secondary osteoarthritis is one of the most common, yet poorly understood, hereditary syndromes of pure and mixed breed dogs. FCP is characterized by fragmentation of the cartilage and subchondral bone on the lateral aspect of the medial coronoid process, with grade II to grade IV cartilage erosion over the center of the medial coronoid process. The pathophysiology of FCP has not been well defined but may include joint incongruity and increased transarticular pressure.
Management of FCP consists of surgical and medical treatments. Surgical management includes removal of fragments and debridement of cartilage lesions, proximal ulnar osteotomy, and total elbow arthroplasty. Studies have historically suggested that when compared with medical treatment, surgical removal of FCP via arthrotomy did not result in improved long-term clinical outcome (e.g., see, Read 1990, Bouck 1995, Boulay 1998, Cook 2001). This finding was recently challenged, however, in a study where 247 elbow joints were treated with a conventional arthrotomy and 271 joints were treated by arthroscopy. It was reported that arthroscopy provided better functional results, but that progression of artbrosis was similar following both techniques (e.g., see, Meyer-Lindenberg 2003 VC01).
The purposes of proximal ulnar osteotomy are to alter the biomechanical forces in the elbow joint by redistributing articular loads to alleviate excessive loads on the coronoid process of the ulna. Little is known about the effectiveness of this procedure, with no long term follow up or placebo control studies (e.g., see, Ness 1998). Total elbow arthroplasty (“TEA”) has been reported to achieve success for severe elbow osteoarthritis, but the success in cases with mild to moderate elbow arthritis has yet to be determined (e.g., see, Lewis 1996, Conz 1998, 2001).
Ulnar osteotomies have been used to correct or alter loads across the canine elbow joint for the management of FCP with the goal of correcting radio-ulnar incongruity (e.g., see, Ness 1998). These techniques presume that the proximal ulnar articular surface is elevated above the radial articular surface leading to increased medial compartmental pressure, cartilage degeneration and subchondral bone fragmentation. A joint surface contact study simulating radio-ulnar incongruence did demonstrate that radio-ulnar incongruence results in shifting of contact to the lateral region of the medial coronoid process, the area where fragmentation most often occurs (e.g., see, DeCamp 1993). The study also evaluated the effect of proximal and distal ulnar osteotomies on correction of the incongruity. A proximal ulnar osteotomy stabilized with an intramedullary pin did restore normal contact patterns in the in vitro model; however, radio-ulnar incongruence has not been definitively identified as the cause of FCP. In the absence of this incongruence, an osteotomy of the ulna may lead to varus deformity of the limb and subsequently increased loads on the medial compartment.
Thus, there exists a need for an improved treatment of the canine elbow joint, as well as a related bone plating system for this improved treatment.